Lithium-organic electrolyte secondary batteries suffer of limited rechargeability mainly due to the poor cyclability of the lithium metal electrode. In fact lithium is unavoidably attacked and/or passivated by any organic electrolyte: this results in non-uniform lithium deposits which, on cycling, assume a progressively dendritic morphology. Furthermore, part of the deposited lithium is isolated from the substrate and thus cannot be electrostripped in the subsequent discharge; accordingly, the cycling efficiency rapidly declines.
A possible solution to this problem consists in replacing the lithium metal electrode with a non-metal lithium electrode having no tendency to be attacked and/or passivated by the organic electrolyte. This approach has been proposed in the particular case of rechargeable lithium batteries based on two dichalcogenide electrodes (U.S. Pat. No. 4,194,062). However, in order to attain high-voltage, high-energy density lithium batteries, the non-metal negative electrode must fulfil the following requirements:
high lithium activity, i.e. low voltage when coupled with lithium; PA0 high capacity, i.e. a high number of lithium equivalents which can reversibly react per mole of electrode material; PA0 small voltage variation during operation; PA0 fast lithium exchange, i.e. high power; PA0 low specific weight.
These requirements are not simultaneously fulfilled by the transition metal chalcogenides which have been so far proposed as positive electrodes (U.S. Pat. No. 4,035,555) or both for negative and positive electrodes (U.S. Pat. No. 4,194,062).